134 NAIL-TAILED WALLABY CHAP.
by Banks. It is said that 15 or even 20 feet are covered at
a bound, and in bound after bound. But in walking slowly it
can be readily seen from an inspection of Kangaroos at the
Zoological Society's Gardens that the animal does rest upon its
tail, which with the hind-legs forms a tripod.
Petrogcde with six species comes next to Macropus, and is
indeed only to be differentiated from, it by the thickly-haired
and more slender tail, which is not used, as it is sometimes in
the Kangaroos, as an extra hind-limb. The Hock-Kangaroos live
among rocks, which they climb, and from which they leap ; and
the tail acts rather as a balancing pole. The most elaborate
account of the anatomy of Petrogale known to me is by Mr.
Parsons.1 The dentition as given by Mr. Thomas is I -j- C -g
Pm •§• M %—that of Macropus without the occasionally occurring
canine of the upper jaw. The osteological characters which
separate it from Macropus are quite insignificant. Mr. Parsons
mentions a wormian bone, " os epilepticum," at the junction oi
the coronal and sagittal sutures. It was found to occur in two
out of five skulls examined, and appears not to occur in other
Kangaroos. The palatine foramina of Petrogale are so large that
the posterior part of the bone is only a narrow thickened ridge.
The small intestine of P. xanthopus is 102 inches long, the
large intestine 44 inches. The caecum has a length of 6 inches,
and is not sacculated, differing in this from the caecum of
Macropus major. The best known species are P. wanthopus and
P. penicillata. The genus is confined to Australia itself, and
does not enter Tasmania.
OwycJiogale includes the so-called "Wail-tailed Wallabies,"which
have a thorn at the end of the tail, reminding one of the Lion and
the Leopard, whose tails have a similar armature. The muffle is
hairy. Three species are allowed by Mr. Thomas.
Lagorchestes has> like the last genus, the rhinarium, i.e. that
part of the nose immediately surrounding the nostrils, hairy
instead of smooth as in the Kangaroos proper. It is distinguished
from Onychogale by the absence of the terminal callosity to the
tail, which is rather short. The name Hare-Kangaroo is given
to the members of this genus (three species) on account of
their exceeding fleetness. This genus is limited to Australia
itself. L. conspicillatus is said to present " a remarkable resem-
1 JVoc. Zaal, Soc. 1890, p. 683.